JPS608994B2 - Curing method for hydraulic inorganic board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for curing hydraulic inorganic boards.

When curing hydraulic inorganic boards with moist heat, the uncured boards are generally placed in a curing chamber, and steam is blown into this curing chamber to maintain a high temperature inside the room and raise the temperature to cure and harden the uncured boards. However, in order to raise the temperature in the curing room to a high temperature, the relative humidity in the room should be adjusted to 90-100%.
It is difficult to maintain such high humidity, and therefore, even under such moist heat curing, drying occurs as the board temperature rises.

This drying process occurs faster at the edges of the board, especially if the board is 3x6
If the board is large in size, such as 4.5 x 10 shaku, there will be a large difference in moisture content between the edges where it dries quickly during curing and the center where it dries slowly. There was a risk that cracks would occur in the board at the edges due to drying shrinkage at the edges. Even if cracks do not occur during curing, when drying a board that has a large difference in moisture content between the edges and the center during natural curing or drying after curing, the drying of the board will proceed from the edges. In the process, the difference in moisture content between the edges and the center became even larger, resulting in cracks occurring at the edges of the board. The present invention has been made in view of the above points, and provides a hydraulic inorganic board that is free from the risk of cracks occurring in the hydraulic inorganic board during moist heat curing, natural curing, and drying processes. The purpose is to provide a curing method.

The present invention will be explained in detail below.

Hydraulic inorganic hardened boards include cement boards, gypsum boards,
A calcium citrate plate or the like can be used, and an uncured plate is obtained by shaping the slurry into a sheet according to a conventional method and applying dehydration pressing or the like.

A large number of uncured plates are stacked between iron plates, etc., and then transported to a curing room.

Steam is blown into the curing chamber to provide moist heat curing. After 3 to 4 hours have elapsed since the uncured board was placed in a curing chamber and the curing had progressed, water was poured only on the edges of the board and the moist heat curing was continued. If water is applied to the board before it hardens, there is a risk that the board will become soggy, or that the water will turn into hot water during moist heat curing, which will prevent hardening and reduce the strength of the board at the edges. After the moist heat curing is completed in this way, the board is allowed to naturally cure, further dried, and finished by painting or the like to produce a final product such as a building board.

As described above, in the present invention, when the hydraulic inorganic board is subjected to moist heat curing, when the curing of the hydraulic inorganic board progresses, water is applied to the end of the hydraulic inorganic board, and the wet heat curing is continued. Therefore, water is replenished at the edges of the hydraulic inorganic board during the moist heat curing process, which slows down the drying process at the edges and reduces the difference in moisture content between the edges and the center. It can be made small, and there is no risk of cracks occurring during the moist heat curing process, natural curing process, or drying process.

In addition, since water is applied to the hydraulic inorganic board as it hardens, it will not cause the board to become swollen, as would be the case if water was applied before the board hardens, and water would not leak out during moist heat curing. There is no risk that the strength of the plate will decrease at the edges due to hot water forming and interfering with curing. Next, the present invention will be specifically explained using examples.

Example 1 Voltland cement 10 parts by weight Asbestos (class 5) 12 Exposed kraft pipe 2'' Silica powder 5 The above mixture was dispersed in water to prepare a slurry, and this was mixed in a conventional manner. Formed into a sheet using a Hacheck type paper making machine, and then subjected to a dehydration press as usual, lmxl.9
An uncured board with a skin size of 6 ribs and a moisture content of about 20% was obtained.

This uncured plate was loaded by 5 women while inserting an iron plate between them,
Place it in a curing chamber where steam can be input and output, and the ambient temperature is 80℃.
Curing was carried out by controlling the amount of steam so that the temperature reached 0.00.
After 24 hours have passed, the uncured boards are thoroughly sprayed with water from around them, and then cured under the same conditions under moist heat for another 4 hours.The cured boards are taken out of the curing chamber and the areas around the edges and center of the boards are cured. The moisture content was measured. Edge approximately 15%
3 Central part: Approximately 16.5% This board was removed from the steel plate and reloaded, left to stand naturally for one week, and then dried in a 12,000-degree hot air drying oven, but no cracks appeared at the edges. .

In this way, an asbestos-cement board with a specific gravity of about 1.9 and an average moisture content of 83% was obtained. Comparative Example 1 An asbestos cement board was obtained in the same manner as in Example 1, except that water was not applied to the edges during moist heat curing.

The moisture content of the board after moist heat curing was approximately 11% at the edges and approximately 16% at the center, with a large difference of 5%. When this was observed after one week of natural curing, slight cracks were observed at the edges of the top several sheets of the stacked boards.

Furthermore, cracks were observed at the edges of about half of the plates during drying in the drying oven. A plate substantially the same as in Example 1 was obtained except for the occurrence of cracks.

Example 2 Calcium aluminate monosulfate hydrate (3Ca○・Ai2○3・CaS○4・1pan0)
10 Rumored part dihydrite pipe
45 Pulp (unbleached kraft pulp) 10
〃Glass (chopped strand, alkali-resistant 1/2 inch cut) 5〃Disperse the above mixture in water to prepare a slurry, form it into a sheet using a fourdrinier paper machine as usual, and then An uncured board with a size of 3 x 1.5 skin and a thickness of 1 rib was obtained by dehydration pressing according to the method.

I used this board to insert a plywood board and played the first part of the sentence in 5. This product was placed in a moist heat curing room with an ambient temperature of 9000°C, and after 3 hours had passed, the Sakama Dan was sprayed with water and left to cure for another 7 hours. continued.
After removing the plywood plate from this plate, it was dried and dehydrated in a hot air drying oven controlled at 150-10 to obtain a plate having a specific gravity of 0.3, a bending strength of 100 k9/piece, and an average water content of 5%.
No plate edge cracks occurred throughout each operation. Comparative Example 2 The same procedure as Example 1 was carried out except that water was not applied during moist heat curing.

Claims (1)

[Claims] 1. When moist heat curing a hydraulic inorganic board, it is recommended that water be poured onto the end of the hydraulic inorganic board when the hardening of the hydraulic inorganic board progresses during the moist heat curing process, and then the moist heat curing should be continued. A characteristic curing method for hydraulic inorganic boards.